1. Field of the Invention
The present invention relates to a sheet feeding apparatus equipped with a sheet feeding tray that can rotate to open or close, and a recording apparatus and an image reading apparatus equipped with the sheet feeding apparatus.
2. Description of the Related Art
In a recording apparatus that records an image on a recording medium or an image reading apparatus that scans an image from an original, a sheet feeding apparatus is used to feed a recording medium in sheet form or a sheet as an original to an image forming portion or reading portion of the like. Examples of a recording apparatus include a printer, a copier, a facsimile, and a multifunction device or system using these. Examples of an image reading apparatus include a scanner and a multifunction device or system using the scanner. In the present application, the term “image” is used in a broad sense to include characters, symbols, line drawings, patterns and the like.
A sheet feeding apparatus comprises a sheet feeding tray for stacking sheets. As described in Japanese Patent Application Laid-Open No. H11-301045, a sheet feeding apparatus is known in which a sheet feeding tray is mounted in a condition whereby it can open and close in a rotatable manner. FIG. 12 is an oblique perspective view of a recording apparatus equipped with the conventional sheet feeding apparatus that shows the sheet feeding tray in an open state. FIG. 13 is an oblique perspective view of the recording apparatus of FIG. 12 that shows the sheet feeding tray in a closed state. According to the sheet feeding apparatus having the sheet feeding tray that can rotate to open or close as shown in FIG. 12 and FIG. 13, closing a sheet feeding tray 101 to store it inside the apparatus enables space saving and enhancement of aesthetic characteristics, and reliability can also be improved as the inside of the apparatus is protected from dust and the like. Further, according to this sheet feeding apparatus, a side guide is provided in the main body and the sheet feeding tray 101, respectively, for regulating the position and inclination of sheets by contacting against the side edge of stacked sheets.
More specifically, on the main body side a side guide 102 is provided as a positioning member that positions sheets, in the width direction (direction parallel to the feeding plane and perpendicular to the feeding direction) by contacting against the side edge in the vicinity of the leading end of sheets that are stacked in the sheet feeding tray. At the top part of the sheet feeding tray 101 that is capable of rotating to open or close is provided a side guide 101a as an inclination limiting member that limits an inclination within the feeding plane of sheets by contacting against the side edge of stacked sheets at a position further upstream than the side guide on the main body side. When the sheet feeding tray is in a folded-up state, the side guide 101a is contained in a recess portion formed in the upper case of the sheet feeding apparatus. According to this sheet feeding apparatus, the skewing of sheets can be reduced while still allowing the sheet feeding tray to open and close in a rotatable manner.
However, in the above described conventional example, it is only possible to provide the inclination limiting member 101a in a limited area at the top part of the sheet feeding tray due to space concerns or the configurational relationship with other constituent members when the sheet feeding tray 101 is folded up. Thus, an inclination limiting effect can not be expected after the rear end of a sheet passes the inclination limiting member. Further, an inclination limiting effect can also not be expected in the case of a sheet whose rear edge does not reach the inclination limiting member because the dimensions of the sheet in the length direction are short. Consequently, the conventional technology attempts to equalize a resistance force or a sheet feeding force that act on a sheet while it is being fed by disposing a plurality of sheet feeding means and a plurality of separation means in the sheet width direction in a well balanced manner and making it possible for them to move in the sheet width direction, to thereby reduce skew feeding of sheets. In this case, the inclination limiting member 101a is used in an auxiliary manner.
Further, in a sheet feeding apparatus in which priority is given to simplification of the apparatus or weight reduction, simplification and weight reduction with respect to sheet feeding means or separation means has been attempted by imparting the principal feeding force to a sheet at a fixed position at one location that is nearer the positioning member than the center of the width direction of the sheet. According to this configuration, skewing of a sheet is liable to occur since the balance of the feeding force or resistance force in the width direction of a sheet is poor. In order to avoid this kind of problem, a large inclination limiting member is provided in the sheet feeding tray and a positioning member provided on the main body side is made larger to simultaneously exert an inclination limiting effect.
However, in a common sheet feeding apparatus, since a sheet bundle comprising a plurality of sheets is stacked in the sheet feeding tray and only the uppermost sheet thereof is separated and fed, it is necessary for the height of the above described positioning member or inclination limiting member to be at least greater than or equal to the thickness (stack height) of the bundle of sheets. Consequently, disadvantages have arisen such as it being spatially impossible to store or fold up the sheet feeding tray, or the number of sheets that can be stacked in the sheet feeding tray being reduced. Other disadvantages include the fact that the size of the sheet feeding apparatus becomes large when the sheet feeding tray is folded up and stored, and the size of the main body side of the sheet feeding apparatus increases. Furthermore, since a sheet feeding tray comprising the inclination limiting member is supported by an external cover, a position of the inclination limiting member with respect to the positioning member is positioned via a sheet feeding frame, the external cover and the sheet feeding tray. Therefore, the position deviation precision in the width direction of the sheet is low, and skewing of the sheet can not be adequately suppressed.